Only a few techniques are capable of the resolution and frequency response necessary for auditory system motion measures; i.e., 10-2 - 102 Angstroms across 100 Hz-20 kHz bandwidths. Previous theoretical and experimental efforts have led to determination of intrinsic performance limits and identification of the parameters relevant to optimization for given objectives. These analyses showed optic lever systems to be competitive with interferometric and optical heterodyneing techniques and better than capacitive probe techniques in resolution and an order of magnitude simpler and less expensive than either. Continuing refinement and explorative efforts have been focused in three areas: experimental determination of the optimum probe size/linear range trade-off and development of automatic in site calibration circuitry for umbo/ossicular chain measures; development and testing of high speed differentiation circuitry allowing correlation of mechanical impulses with acoustic emissions from imparted plate and other radiating structures creating occupational noise levels of hearing loss significance; and work on specialized probes for measurement of ossicular membrane vibration.